A Highly Reliable Dual-Mode RRAM PUF With Key Concealment Scheme

Physical unclonable function (PUF) has been widely used in the Internet of Things (IoT) as a promising hardware security primitive. In recent years, PUFs based on resistive random access memory (RRAM) have demonstrated excellent reliability and integration density. Most previous designs store PUF keys directly in RRAMs, increasing vulnerability to attacks. This article proposes a dual-mode RRAM PUF, named differential mode and flexible mode, utilizing the difference in switching capability between RRAMs during parallel SET operations as the entropy source. The proposed PUF can reliably reproduce keys between cycles, so a key concealment scheme is used to protect PUF keys from being continuously exposed, improving the security of the RRAM PUF. The proposed RRAM PUF exhibits high reliability over ±10% VDD and a wide temperature range from −25°C to 125°C through post-processing operations. The flexible mode can generate a significant number of keys for high-security applications. Since the PUF keys can be concealed, the proposed PUF is compatible with in-memory computing. It can be implemented using the same RRAM array as experimentally validated using a MAGIC operation, thus reducing the hardware overhead.